MilkDrop is a music visualizer - originally a "plug-in" to the Winamp music player, and now available as OSS.
As you listen your music in Winamp, MilkDrop 2 takes you flying through visualizations of the soundwaves you're hearing, and uses beat detection to trigger myriad psychedelic effects, creating a rich visual journey through sound. MilkDrop 2 can also be driven by a live audio feed (microphone or line-in) - see the documentation for details.
Milkdrop2 is the best, what can I say... It'd be nice if it were made even better!
Amazing visualizer. Hands down the best one I've ever seen. It truly is out of this world even though some times it can be a bit "off" PS: For the "Support" I'm not giving a rating as I have not requested or searched for any support